From DE 11 2012 002 419 T5 there is known a centrifugal blower of an air conditioning system in a motor vehicle of this kind, with a centrifugal fan, having an electric motor as well as a fan wheel coupled to it firmly against twisting. The centrifugal blower furthermore has a fan housing with an air inlet and an air outlet, which at the same time receives the centrifugal fan inside it. The electric motor of the centrifugal blower is fixed in a motor bracket, having a cylindrical shape and possessing a collar extending outward in the radial direction, on which a circumferential water protection ring is arranged, situated radially inward and extending upwardly in the axial direction. This water protection ring is supposed to prevent a penetration of water into the motor.
From DE 10 2010 027 377 A1 there is known another centrifugal blower for an air conditioning system in a motor vehicle with a housing and with an impeller, whose vanes are coupled to a hub of the impeller via a carrier. The carrier is impermeable to water droplets in the axial direction of the impeller and extends in the radial direction beyond the respective outer edges of the vanes of the impeller. Furthermore, a water retention wall disposed on the housing, with the carrier extending beyond it, ensures that water droplets taken in cannot get to a drive motor of the impeller.
In general, the water separation process in motor vehicles is getting functionally worse on account of increasing cost pressure and steadily diminishing available design space, so that more and more water is getting into an air conditioning system with the fresh air taken in across an end wall. Filters, especially filters installed at the factory, already reduce the water fraction substantially, but do not entirely prevent water droplets from getting into the motor and causing damage there, at least in the long term.
Furthermore, for the cooling of the motor of a centrifugal blower the cooling air is taken in downstream from the filter, so as to take clean, dry air through the blower motor. This cooling air flows through an annular gap and is separated once more in a region beneath the motor. Even so, water can also collect in this case underneath a fan wheel and get into the motor region in an unwanted manner. For example, this can occur or be intensified in violent rainstorms or also in car washing facilities due to penetration of a water surge, especially if drains on the vehicle are plugged up.